mod cache;
mod messages;

use cache::Cache;
use messages::{ReceiveMsg, SendMsg, SessionRequest};
use std::{
    sync::mpsc::{channel, Sender},
    thread::spawn,
};
use uuid::Uuid;

/// Application connection to the database
#[derive(Clone)]
pub struct MoreThanText {
    id: Option<Uuid>,
    tx: Sender<SendMsg>,
}

impl MoreThanText {
    /// Create a MoreThanText database.
    ///
    ///  Example:
    ///
    ///  ```
    ///  use morethantext::MoreThanText;
    ///
    ///  MoreThanText::new();
    ///  ```
    pub fn new() -> Self {
        let (tx, rx) = channel();
        spawn(move || {
            let mut cache = Cache::new(rx);
            cache.listen();
        });
        Self { id: None, tx: tx }
    }

    /// Opens an existing or new session with the database.
    ///
    ///  If the string is None, incorrect, or expired,
    ///  a new session will be created.  
    ///
    ///  Example:
    ///
    ///  ```
    ///  use morethantext::MoreThanText;
    ///
    ///  let mut mtt = MoreThanText::new();
    ///  mtt.open_session(None);
    ///  mtt.open_session(Some("7b1ff340-7dfa-4f29-b144-601384e54423".to_string()));
    ///  ```
    pub fn open_session(&mut self, id: Option<String>) {
        let (tx, rx) = channel();
        let request = SessionRequest {
            id: id,
            tx: tx,
        };
        self.tx.send(SendMsg::OpenSession(request)).unwrap();
        match rx.recv().unwrap() {
            ReceiveMsg::Session(sid) => self.id = Some(sid),
        }
    }

    /// Get the session id
    ///
    /// Example:
    ///
    /// ```
    ///  use morethantext::MoreThanText;
    ///
    ///  let mut mtt = MoreThanText::new();
    ///  mtt.get_id();
    /// ```
    pub fn get_id(&self) -> String {
        match self.id {
            Some(sid) => sid.to_string(),
            None => "none".to_string(),
        }
    }
}

#[cfg(test)]
mod mtt_client {
    use super::*;

    #[test]
    fn uniques_ids() {
        let mut mtt = MoreThanText::new();
        let mut ids: Vec<Uuid> = Vec::new();
        for _ in 1..10 {
            mtt.open_session(None);
            let id = mtt.id.clone().unwrap();
            if ids.contains(&id) {
                assert!(false, "{} is a duplicate id", id);
            }
            ids.push(id);
        }
    }

    #[test]
    fn existing_ids_are_reused() {
        let mut mtt = MoreThanText::new();
        mtt.open_session(None);
        let holder = mtt.id.clone().unwrap().to_string();
        mtt.open_session(Some(holder.clone()));
        assert_eq!(mtt.id.clone().unwrap().to_string(), holder);
    }

    #[test]
    fn bad_ids_generate_new_ones() {
        let mut mtt = MoreThanText::new();
        mtt.open_session(Some("bad test string".to_string()));
        assert!(mtt.id.is_some());
    }

    #[test]
    fn incorrect_ids_generate_new_ones() {
        let mut mtt = MoreThanText::new();
        let holder = Uuid::new_v4();
        mtt.open_session(Some(holder.clone().to_string()));
        assert_ne!(mtt.id, Some(holder));
    }
}